Heat Grill pan.,Pour vinager into sauce pan add garlic.,Heat vinager on a medium low heat.,rub olive oil onto steak,Salt steak on both sides useing kosher salt add pepper,Grill steak to your likeing.,Remove steak to plate.,______,Saute onions & mushrooms til golden brown season with salt & pepper when sauteing.,plate steak add balsamic sauce & top with sauted onions & mushrooms.,Enjoy!,!